Manufacture of sugar



MANUFACTURE O F SUGAR Filed Dec. 4, 1928 y i. :1 l: i: il.

0. 40 4/ 3 J0 i5 5 3/ l z/ :4 ze f2@ ,27 J4 v j if vINVETIO-R Patented Apr. 22, 1930 UNITED STATES PATENT OFFICE ARTHUR W. BULL, 0F NAUGATUCK, CONNECTICUT, ASSIGNOR T0 THE DORR COMPANY. OF NEW YORK, N. Y., A CORPORATION 0F DELAWARE MANUFACTURE OF SUGAR Application med December 4, 1928. Serial No. 323,640.

beets are Washed and then sliced into cossettes.y

The sliced beets are next subjected to a counter current iiow of Warm Water under pressure, in a so-called diEusion battery. The diffusion juice is dark in color and contains 1n suspension or solution the colloidal and soluble contents of the beet, i. e., sucrose, potassium and sodium salts of phosphoric, su furic, hydrochloric, oxalic, and tartaric acids, proteins, pectins, albumen, etc., and a small amount of invert sugar. The sugar content of the juice varies from about 9 to 16% by weight. In reaction it is slightly acid. The suspended fibre, cellular tissue and coagulated albumen are separated from the juice. The juice is then heated to about 85 C., which has the e'ect of coagulating aportion of the albumen, besides preparing it for clarification.

Lime, usually in the form of milk of lime, or-

calcium saccharate, is added to the hot juice in amount varying from 2 to 3% of the weight of the beets employed. This throws the juice from its acid to an alkaline state. The limed juice is frequently subjected to prolonged agitation, varying from 15 to 20 minutes, at an elevated temperature.

The limed or defecated juice is subsequently subjected to a so-called carbonation step, which consists in subjecting the juice to gas containing about 30% carbon dioxide. As a result of this treatment, calcium carbonate is precipitated. As many as five tanks are employed in the carbonation step. The operation is usually carried on in batches. One

tank of the limed juice is subjected to the carbon-ation step, while the other tanks are being prepared for the same operation. When the `gas isfirst introduced into the limed juice, a gelatinous and practically non-settling material is produced. As gassing is continued,

the nature of the precipitate changes, and when the alkalinity has been reduced to about OJO-0.15 grams of lime (calcium oxide) per 100 cc. of filtrate, the precipitate becomes fl'occulent and it can be readily settled or filtered. If the gassing is contmued, and the alkalinity of the juice is still further reduced, the precipitate becomes more and more flocculent, but a point is soon reached where some of the impurities that have been removed from .the solution begin to go back into solution.

This heretofore customary practice of manufacturin complex, involves many operations, and requires the attention of very skilled operators.. For example, if the'first carbonation step is carried too far or is not carried far enough, it is substantially impossible to obtain a clear filtrate. In other Words, unless the gassing operation is conducted to a precise end point, it is substantially impossible to obtain a clear separation of solids from liquids. Due to the fact that the operations are conducted in batches and the controls are all exerted manually, by turning valves, it has been extremely difficult to obtain substantially uniform purified and clarified sugar juices at the end of the process.

As a result of my investigations, I have determined that the treatment of beet juice in the manufacture of sugar may be greatly simplied and made far more eflicient than is the case in the present practice. The purifying and clarifying steps may be accurately controlled, a better separation of solids and liquor may be effected, and the beet juice obtained at the end of the process is of a uniformly high grade.

In accordance with the practice of the present invention, beet juice is treated for the manufacture of sugar in such manner that the dissolved lime in the juice does not reach the saturation point. This may be accomplished either by introducing into the juice an amount of lime substantially less than that which will produce saturation when completely dissolved, or by subjecting the juice to the action of carbon dioxide or the like so promptly after the introduction into the juice of the lime that the lime does not have sufiicient time to form a saturated solution, and thereafter gassing the juice continuously ata rate that wlll prevent saturation. To this end, the invention involves the step of addin lime-only to juice that is being substantial y simultaneously gassed. My invention also contemplates mixing raw diffusion juice with previously carbonated juice before subjecting the-raw juice to a gassing operation. The present invention also contemplates the step of repeatedly circulating such juice, at least in part, throu h a gassing zone. In the present preferre practice of the invention the above steps are advantageously combined, though the may also be used singly'.

n referring to carbonation herein; the expression is used in the sense customary in the art to indicate the usual treatment with carbon dioxide or its equivalent; and imaccordance with customary usage referenCS to carbonated juice are intended to designate juice that has been subjected to such customary carbonation, and which according to the usual practice contains a residual amount of dissolved lime.

In the copending application of Messrs. Ramsey and Bull, Serial No. 107,579, filed May 8, 1926, of which I am a co-applicant, there is disclosed a method and apparatusfor automatically and quickly controlling the carbonation of sugar juices to predetermined degrees of alkalinity. Moreover, the method and apparatus therein described may be employed in such manner as to effect the continuous carbonation of sugar juices by such automatic control. The f 4actice of the invention therein disclosed may advantageously be followed in the practice of the present invention.

ing agent. soluble in the juice, ordinarily comprising a suitable compound of calcium, such as fresh lime or calcium saccharate, to beet juice that is being substantially simultaneous ly gassed offers very important advantages. This step (liming) results in a precipitation of calcium carbonate from a solution much lower in concentrationwith respect to dissolved lime, for example, than is the case j solved lime. In the practice of the present.

when lime is added outs-ide the gassing zone` When the lime is added to the juice some distance away from the gassing zone, and particularly when the limed juice is agitated as in the general practice heretofore resorted to, a sufficient amount of lime will go into true solution to reach the saturation point. Un-

der such operating conditions the initial pre cipitating of calcium carbonate .from the gassing'-zone is from a solution completely orpraetically completely saturated with disinvention, on the other hand, the precipitation of calcium carbonate is effected from a solution of limed juice that' is only partially saturated with lime in true solution.

I have found that the addition of a lim-y It is a very denite advantage to prevent the alkalinity of the juice from ever reaching the high value corresponding to that obtaining when the juice is saturated with respect to dissolved lime. Undei auch circumstancesthe calcium carbonate particles settle very slowly and the mixture may only be filtered with considerable difficulty. rl`he introduction of lime to the raw diffusion juice at some distance and time before the gassin operation, aswell as the agitation of the lime juice, is harmful because 'the 'uice will become saturated with dissolve lime, and a high alkalinity is established. Albuminoids and the likepresent in the juice are attacked by the lime in solution. This reaction produces a relatively large proportion of verytiall y saturated with lime in solution, and a relatively lowalkalinity is established, a Very much smaller amount of the fine colloids is produced. Hence the adsorption of colloids on the surfaces of the calcium carbonate par- -ticles as a result of carefully controlling liming is ymaterially inhibited, and crystal growth is encouraged. The establishment of relatively low alkalinities in the juice by controlled liming aids in the crystallizing step in that fewer and larger calcium carbonate particles are precipitated, since the number and size of crystals increase and decrease, respectively, with increased concentration of lime in solution. The lime in suspension, that is, undissolved lime, has no effect as such on the alkalinity of the juice, and hence plays no important rolein the reactions just discussed. High alkalinities are therefore to be'avoided as much as ossible, and I have accomplished this desira le result by introducing the lime into the juice substantially simultaneously with the introduction of the l carbon dioxide as.

valkaline (due to the lime in true solution),

the mixture of the two in proper proportions gradually renders the raw juice alkaline. The purification of the juice is both mechanically and chemicallyefl'ected. The mechanical purification is due to the fact that the suspended calcium carbonate particles become covered or coated with colloidal matterl in suspension throughout the raw juice. A portion lof these colloidal constituents contact with and are adsorbed on the calcium carbonate particles. The removal of such colloidal matter in this manner aids the further nor-v 85 the other hand, when the juice is only parample, `raw tains some sodium phosphate in solution.'

lticularly fostered Qn such carbonate particles stood by mal precipitation of calcium ycarbonate articles, since such adsorbed colloids are e ectively removed from the reaction zone.

In addition to `the mechanical removal of colloidal constituents, as just pointed out, certain chemical reactions take place to purify the juice. Dissolved lime in true solution re'- acts chemically with certain dissolved im puritiesvin the raw juice, such as potassium and sodium salts of phosphoric, sulfuric, oxalic and tartaric acids, to form substantially water-insoluble compounds. For exdiusion juice undoubtedly con- Sodium phosphate reacts with the lime in solution to form relatively water insoluble calcium phosphate. As the carbonated and raw juices are circulated, the solids in suspension contact with one another and tend to build into larger particles or agglomerates that are readily separable from their liquid vehicle either by settling or filtering. Such water insoluble particles also operate to purify the juice mechanically by adsorption on their surfaces ofobjectionable 'colloidal matter.

In this manner raw diffusion juice eventually reaches the gassing zone in at least a partially purified condition. As a result of this preliminary purification, the 'surfaces of the freshly precipitated calcium carbonate particles formed during the gassing period. are

. less contaminated with colloidal matter than in the process heretofore practiced. The substantially clean surfaces of the freshly precipitated calcium carbonate particles lend themselves to particle growth. Such article growth( increases the average size o the calcium carbonate crystals, which is particularly desirable for eiiicient and rapid settling and filtering.

. Marked advantages are to be obtained when carbonated juice is, at least in part, repeatly circulated through'a gassng zone. Such recirculation ofvcarbonated juice tends matebuilding-up 'of vcalcium rially to aid in the Particle growth is parcarbonate particles.

recirculated as have substantially vclean surfaces. It is therefore prefer-red to colnbine this feature of recirculation with the steps outlined above.

The calcium Ccarbonate ,precipitation step itself is materially aidedby the presence of previously precipitated `calcium j carbonate particles. That is to say, bonate particles tend to act as nuclei for the precipitation offurther amounts of calcium carbonate out of-solution.

These and other advantages of the present invention will, it is believed, be better underreference to the accompanying drawing, taken in conjunction with the following description, in' which is 'diagramniatcally'shown a for of apparatus adapteod practice the invention.

i a sight-box 15.

individual calclum- 'tents of tank`2 or the calcium car-l vided with outletvents at thel tops thereof for the escape of unabsorbed gas. A juice storage tank 4, preferably located at a level above the main treatment tanks, means of pipe 5 with a. constant level tank v6. This latter tank is provided with a float valve 7. The constant level tank connects with the irst treatment tank 1 by means of a pipe line 8. This pipe line is provided with a chain operated valve 9.

A lime storage tank 10, preferably located at a level above the main treatment tanks, connected by means of a pipe 11 with a constant level tank 12. This constant level tank is also provided with a float valve 13. A pipe line 14 connects the constant level tanks and This box contains a. wcir for the measurement of the amount of lime passing therethrough. The pipe line `Y is equipped with a chain operated valve 16. Carbonation tanks 2.and-3 areconnected to the sight-box by means of pipe lines 17 and 18, both pipes being provided with valves 19 and 20, respectively.

The main treatment tanks 1, 2 and 3 are appropriately interconnected by means of suitable pipe lines. Tank 1 connects with tank 2 by means of a pipe line 21 that extends from the bottom of tank 1 to near-the middle connects by of tank 2. Another pipe line 22 connects i The pipe line 27 is provided with a loop 32 to maintain the level ofcarbonated juice in the tanks at a desired point. A vent 33 is providedin the loop to overcome anyv Siphon action that may develop in the feed line to the thickener.

Tanks 2 and 3 also connect at their bottoms by means of pipes 25 and 26, respectively, with `.a recirculating pipe line 34, provided with a valve 35. The recirculating line is provided with a pump 36 to force the contank 3 to tank 1. Tanks 2 and 3 are suitably connected with gas distributing means. yA main gas line 37 is provided with offtake pipes 38 and 39, having valves 3 8 and 39', at tanks 2 and 3, respectively. These otake pipes are in turn connected with a plurality lof'distributors 40 and 41, leading into tanks 2 and 3 near the lbottoms thereof. A constant pressure regu-l lator 42 is provided in the main gas line 37.

The main gas line is also provided with a plication above referred to.

' The apparatus just described may be operated as follows: Raw diffusion juice is fed into storage tank 4. A suicient amount of this juice is conducted by gravity into tank 6 to build up a constant pressure as indicated and determined by the float valve 7 The chain operated valve 9 is suitably opened to conduct the beet juice through the pipe line 8 into the rst treatment tank 1. Beet juice is passed from tank 1 by means of pipe line 21 into the carbonation tank 2, until tank 2 is filled to its working level. Valve 24 in the pipe line 22 leading to tank 3v is .closed while tank 2 is in operation.

Milk of lime is fed into the storage tank 10, and iinds its way by gravity through pipe 11 into the constant level tank 12. The chain operated valve 16 is suitably opened to conduct the milk of lime through the sight-box ff' 15. Valve 20 in line 18 leading to tank 3 is closed so that the milk of lime may pass through pipe 17 intotank 2, where it mixes with the beet juice.

When the tanks are filled to their normal operating level, the juice and lime supplied are temporarily shut off, the recirculation pump 36 is started and gas is admitted for the carbonation of the mixture already in the tanks.

Carbon dioxide gas in fed through the main gas line 37. The pressure of the gas fed to the line is suitably regulated by the pressure valve 42. The valve 39 in otake pipe 39 leading to tank 3 is closed so that the gas may be fed into tank 2. Since the gas is made to enter the mixture of beet juice and milk of lime near the bottom of tank 2, the bubbles of gas percolate up through the bodyof liquid.

When the carbonation has proceeded to the usual end point, the supply of 'juice and lime is again started, valve 31 is opened and the process is then under continuous operation.

A portion ofthe carbonated juice is conducted from the bottom of tank 2 through lines and 27 into thesettling or thicke ing device 28, while the remainder is pumped into tank 1. The recirculation of carbonated juice is conducted, in the present preferred practice of the invention, at a ratio of eight to one. That is to say, about eight volumes of juice are recirculated for each volume of new juice added to the circuit. Completely' carbonatedjuice is conducted to the settling or filtering device as rapidly as raw diffusion juice is fed into thesystem. In this manner beet juice may be continuously carbonated.

It will be observed that the addition of milk of lime to the juice in tank 2 is made La while the mixture is being gassed. There is Thislrious ways.

no agitation of juice with lime lpreceding' the carbonation step. lRising bu bles of gas strike the juice substantially as soon as it is mixed with lime. The interval of time between liming and gassing is negligible under operating conditions. The object is to gas the limed juice before the juice is saturated with respect to lime in true solution. In other words, the juice is gassed when it is butpartially saturated with lime, or when its alkalinity is relatively low compared with what it would be when completely saturated with lime vin true solution.

Since carbonated juice from tank 2 is made to mix with raw diffusion juice in tank 1, it is apparent that the purifying step above discussed takes place. The carbonated juice contains calcium carbonate particles in suspension. These particles operate mechanically to purify the raw diffusion juice in tank 1 before it reaches the gassing zone in tank 2. Colloidal matter present inthe raw juice contacts with` and is adsorbed on these suspended calcium carbonate particles.

The lime in true solution removed from tank-2 totank 1 operates chemically to purify the raw juice. This lime reacts with certain dissolved salts and the like in the raw juice to form compounds that are soluble in the mixture. Colloidal matter also contacts with and is adsorbed on these insoluble particles. l

B the time the raw juice from tank 1 reaches the liming and gassing zone in tank 2, it is materially purified. This juice may then be gassed for the precipitation of fresh calcium carbonate particles without colloidal matter being immediately adsorbed on their surfaces. Clean calcium carbonate particles readily, lend themselves to particle growth,

and, moreover, act as nuclei in the precipita-A tion of calcium as calcium carbonate.

,@Whenever it is desired to shut down tank 2, for example, to clean the gas distributor or tank, the valves inthe pipe lines leading to this tank may be closedand those in the lines leading to tank 3 may be opened to throw it into operation.

It will be understood that the present inf vention is not to be confined to practice in apparatus above discussed. The. invention may obviously be conducted in other and va- For example, instead of employing separate tanks in association with one another, such as tanks 1 and 2 or 1 and 3, one relatively high'tank might very well be employed. The upper end of such a single tank, suitably -balled from the lower end,

might serve as a place in which to mix raw substantially into those skilled in this art, in view of the f having a given composition and purity, a.

definite amount of the liming agent will be required for proper defecation, and a Vcorresponding amount of carbon dioxide gas or the like will be necessary to reduce the alkalinity of the carbonated juice to the requisite point. Where juice is carbonated by the former batch method, the rate of introduction of the lime relative to the rate of gassing can be regulated as desired; but where the juice is owing continuously through a treatment zone, it is necessary to add the lime at a fixed rate determined by the proportion of lime to juice required by the purity, etc. of the latter; and a reduction in the rate of lime addition will result in inadequate liming. A

problem of the present invention involves the maintenance of the necessary continuous flow of lime without producing saturation of the juice with limeat any point; and the disclosed arrangement has solved this problem by providing a suitable method of introducing juice and lime at the top of the relatively narrow tanks directly in the active gassing zone, so that withdrawal of the carbonated or partially carbonated juice and calcium compound crystals beneath the carbonation zone will produce a uniform downward flow against a uniform upward gassing action, thereby preventing all parts of the juice from `becoming saturated with the liming agent at any time.

I claim:

1. The method of treating beet juice in the manufacture of sugar which comprises limingand carbonating beet juice substantially simultaneously, mixing said limed and carbonated juice with raw beet juice, and subjecting said mixed juice to carbonation.

2. The method of treating beet juice in the manufacture of sugar which comprises incompletely saturating the juice with lime, carbonating said limed juice, mixing said carbonated juicewith raw juice, andcarbonating said mixed juice.

j 3. The method of treating beet juice in the manufacture of sugar which comprises partially saturating the juice with a liming agent soluble inthe juice, subjecting said partially saturated juice to carbonation, and repeatedly circulating said carbonated juice at least in part through the carbonation zone.

4. The method of treating beet juice in the manufacture of sugar which comprises partially satur'ating the juice with a liming agent soluble in the juice, subjecting said partially saturated juice to carbonation, mixing said carbonated juice with raw juice, and repeatedly circulating said carbonated juice at least in part through the carbonation zone.

bonated and raw juices,

5. The method of treating beet juice in the manufacture of sugar which comprises incompletely saturating the ,juice with linie and then carbonating the partially saturated juice, said juice being in part at least repeatedly rccirculated through the carbonation zone.

6. The method of treating beet juice in the manufacture of sugar which comprises mixing raw juice with carbonated juice. 1

7. The lnethod of treating beet-juice in the manufacture of sugar which comprises mixing raw juice with carbonated juice, and liming said mixture.y

8. The method of treating beet juice in the manufacture of sugar which comprises mixing raw juice with carbonated juice, liming said mixture, and carbonating said limed mixture.' j j A9. The method of treating beet juice in the manufacture of sugar, whidh comprises mixing raw juice with carbonated juice, liming said mixture, and carbonating said limed mixture, said carbonation taking place substantially simultaneously with the liming ste 11i). The method of treatin beet juice in the manufacture of sugar w ich comprises flowing a body of limed and carbonated juice into' a body of raw juice, adding more lime to the mixture ofjuices, and passing said mixture through a carbonation zone.

' 11. The method of treating beet juice in the manufacture of sugar which comprises continuously mixing carbonated juice with raw juice, circulating said mixture through a carbonation zone, and withdrawing carbonatcd juice from the circuit substantially as rapidly as raw juice is introduced into the circuit.

12. The methodv of treating beet juice which comprises flowing a substantially constant stream of the juicey to a liming zone, incompletely saturating the juice with lime, conducting the limed juicey to a carbonation zone, subjecting said partially saturated juice to the action of carbon dioxide gas, flowing la substantial portion of said carbonated juice to the point of introduction of raw juice into the circuit mixing said cariowing said mixed juices to the liming zone, incompletely saturating the mixed juices with lime, conducting the limed juice to the carbonation zone, subjecting said partially saturated juices to the action of carbon dioxide gasreturning a lll() substantial portion of said carbonated juices said zone to the continuous action of carbon dioxide gas, continuously adding a liming agent to 'the vjuice at the beginning of its iow through said zone, and maintaining throughout the juice as -it passes through said zone uniform distribution of said liming agent and gas, adequate to maintain substantially all of said juice in a condition of incomplete saturation with said liming agent 1`0 ,during its passage through the carbonation zone.

14. The method of treating beet juice in l the manufacture of sugar which comprises passingthe' juice downwardly .in continu- 'ous How through a vertical elongated car'y bonation zone of substantially uniform width, subjecting 'juice insaid zone to the continuous action of carbon dioxide gas passing upwardly through the iowing juices, and adding continuously a liming agent to the juice at the top of said zone in the eld of gas action. l

l5. The method of treating'beet juice in the manufacture of sugar which comprises initial treatment of the juice with a liming agent in an amount insuicient to saturate the juice, andthereafter passing the juice in continuous flow through a carbonation zone, subjecting the juice in said zone to the continuous action of carbon dioxide gas, continuously adding an additional amount of a liming agent to the juice at the beginning of its flow through said zone, and maintaining throughout the juice as it passes through :aid zone uniform distribution of said agent and gas ade uate to prevent any substantial portion of t e juiceffrom becoming saturated with the liming agent.

In testimony whereof I aix my signature.

d ARTHUR w. BULL. 

